The present invention relates generally to a method and apparatus for treating suspensions of waste papers and, more particularly, to such a method and apparatus which employs refining apparatus for separating the various pollutant laden-fractions of the waste paper suspension being refined. Separation is achieved primarily by the generation of a turbulent flow in the center of the apparatus by the use of a rotary blade. As a result of the turbulent flow being generated in the housing by the rotary blade, lightweight pollutants are drawn to and tend to accumulate in the center of the housing while the heavier pollutant particles are drawn to and tend to accumulate along the radial edges thereof. Separation is facilitated by the introduction of supplemental compressed air which is fed into the refining apparatus. The compressed air may, in one embodiment of the invention, be admixed with the water paper suspension being supplied to the refining apparatus.
The above described method is accomplished by the use of at least one air pipe which is connected to a suspension inlet pipe and, in certain instances, to a stirrer directing line of the apparatus.
Refining apparatus of this type has been used in the past. For example, similar apparatus is described in West German Patent No. DE-AS No. 25 14 162. Further, processes of the type described above are, oftentimes, used in waste paper treatment technology.
The apparatus of the present invention utilizes a rotary blade located within the housing of the apparatus in order to generate the turbulent flow within the housing. Such apparatus may be considered almost to be a secondary solubilizer of the material and in which the previously dissolved waste paper is further liquified and even partially despecked. The whirling action created by the turbulent flow makes it possible to separate the heavy impurities or pollutants by separately removing different fractions from the suspension. A fraction laden with heavy impurities is drawn off along the radial edge of the flow while a fraction laden with lighter impurities is removed from the center of the flow, i.e., along the extension of the rotor axis.
Against the foregoing background, it is a primary object of the present invention to provide a method for treating waste paper suspensions.
It is a further further object of the present invention to provide such a method wherein the operation of the apparatus is substantially more efficient than using heretofore known methods.
It is still a further object of the presentinvention to provide apparatus for effecting such method.